Magnetic interaction at an interface between manganite and other transition metal oxides

TL;DR

This paper presents a theoretical framework for understanding magnetic interactions at interfaces between manganites and other transition metal oxides, highlighting how orbital occupancy influences magnetic coupling and how it can be manipulated.

Contribution

It introduces a generalized model based on molecular orbitals and Hund's rule to predict magnetic interaction signs at interfaces, including the effects of orbital stabilization and occupancy.

Findings

Magnetic interaction sign is determined by molecular orbital considerations.

Orbital stabilization can invert magnetic coupling at interfaces.

Interfacial magnetic interactions can be tuned by orbital occupancy.

Abstract

A general consideration is presented for the magnetic interaction at an interface between a perovskite manganite and other transition metal oxides. The latter is specified by the electron number $n$ in the $d_{3z^2-r^2}$ level as $(d_{3z^2-r^2})^n$. Based on the molecular orbitals formed at the interface and the generalized Hund's rule, the sign of the magnetic interaction is rather uniquely determined. The exception is when the $d_{3z^2-r^2}$ orbital is stabilized in the interfacial manganite layer neighboring to a $(d_{3z^2-r^2})^1$ or $(d_{3z^2-r^2})^2$ system. In this case, the magnetic interaction is sensitive to the occupancy of the Mn $d_{3z^2-r2}$ orbital. It is also shown that the magnetic interaction between the interfacial Mn layer and the bulk region can be changed. Manganite-based heterostructures thus show a rich magnetic behavior. We also present how to generalize the argument including $t_{2g}$ orbitals.